module Main where

import Control.Monad

main :: IO ()
main = do
    n <- readLn :: IO Int
    let ans = head [x | a <- [2 .. n+100 `div` 2]
                      , b <- [2 .. n+100 `div` 2]
                      , let x = a * b
                      , n - 100 <= x
                      , x <= n + 100
                   ]
    print ans